If `vecA`and `vecB` have angle between them equals to `60^@` and their resultant make, angle `45^@` with `vecA and vecA` have magnitude equal to 10. Then Find magnitude of `vecB`.

Explanation

Here `alpha = 45^@ and beta = 60^@ - 45^@ = 15^@`
so `A sin alpha = B sin beta`
`10 sin 45^@ = B sin 45^@`

`So B = 10/(sqrt2) sin 15^@`
`= 10/(sqrt2) sqrt(1 - cos(2 xx 15))/(2) = 5/(sqrt2) sqrt(2 - sqrt(3))`.